1. Field of the Invention
This invention relates to switching networks and, more particularly, to the type of network which is sometimes known as a nodal or equi-interconnectable switching network. Such switching networks are distinguished from the more well-known plural-stage network arrangements (which are usually engineered to conserve the amount of crosspoints employed) by the fact that the terminations (input and output points) in a nodal network are distributed more or less homogeneously throughout the switching array. Each termination is associated with a respective nodal crosspoint configuration (NCC), which is connected by links to the adjoining NCCs in the switching plane.
2. Description of the Prior art
In one kind of prior art nodal network such as described, for example, in my U.S. Pat. No. 3,916,124, entitled "Nodal Switching Network Arrangement and Control", issued Oct. 28, 1975, each NCC is equipped with the minimum number of crosspoints (10) for establishing connections to and from adjoining NCCs located in any of the four cardinal directions linked to the given NCC, or for establishing a connection from the termination associated with the given NCC to any adjoining NCC in one of these cardinal directions.
In my prior U.S. Pat. No. 3,906,175 entitled, "Multiple Link Nodal Switching Network", issued Sept. 16, 1975, a plurality of links connect each NCC to adjoining NCCs in the cardinal directions in order to provide adequate traffic capacity with low probability of blocking.
In my presently copending U.S. patent application Ser. No. 905,214, filed May 12, 1978, entitled, "Nodal Switching Network with Binary Order Links", each NCC is connected not only to the immediately adjacent NCC in each of the cardinal directions of the switching plane, but is also directly connected to more distant NCCs in these directions by links whose lengths are ordered according to powers of the binary base two. This reduces the number of intermediate NCCs which must be involved in connecting a calling to a called termination.
In all of the foregoing nodal network configurations, and in the prior art U.S. Pat. No. 3,729,593, to O. Altenburger et al., issued Apr. 1973, the maximum number of simultaneously existing connections which the network is capable of supporting is limited by the available number of wire paths linking the NCCs. It would be extremely advantageous to achieve an enhanced degree of traffic handling capacity beyond that exhibited by these prior art nodal switching configurations.